KIEV, Ukraine — Ukraine's embattled President Viktor Yanukovych is taking sick leave, his office announced Thursday, leaving it unclear how involved he may be in efforts to resolve the country's political crisis in which protesters are calling for his resignation.

A statement on the presidential website said Yanukovych has an acute respiratory illness and high fever. There was no indication of how long he might be on leave or whether he would be able to do any work.

The announcement prompted skeptical reactions and even the suggestion that it was a ruse to take him out of power.

"I don't remember official statements on Viktor Yanukovych's colds. But I remember well, when on Aug. 19, 1991, the vice president of the USSR, Gennady Yanayev, announced the serious illness of Mikhail Sergeyevich Gorbachev," political commentator Vitaly Portnikov wrote on his Facebook page.

Gorbachev's purported illness was reported as hardline Communists opposed to his reform efforts attempted an unsuccessful coup against him.